Inflammatory bowel disease (IBD) is a group of chronic inflammatory diseases of the gastrointestinal tract of unknown aetiology. Evidence of abnormalities in immune regulation and cytokine production in patients with IBD has led to investigations of various immuno-regulatory genes as potential candidate susceptibility loci. Studies using whole genome scanning have highlighted chromosomes 3, 7, 12 and 16. A 32 base-pair deletion in the CC-chemokine receptor-5 gene (CCR5-A32, chromosome 3p21.3) has been associated with susceptibility to IBD. We have investigated CCR5 as a candidate susceptibility gene in 350 patients (251 with ulcerative colitis and 99 with Crohn's disease) and 103 controls using polymerase chain reaction. There were no significant differences in the distribution of CCR5 genotypes or frequencies comparing patients and controls, or associations with extent of colitis. In contrast to preliminary data, these findings suggest no evidence for involvement of this mutation in susceptibility/resistance or disease progression in IBD.